On Tue, Apr 29, 2008 at 1:46 AM, mabshoff <[EMAIL PROTECTED]> wrote: > > On Apr 29, 10:33 am, Francois <[EMAIL PROTECTED]> wrote: > <SNIP> > > Hi Francois, > > > > > Once you get some answer from upstream please open a ticket. I find it > > > odd that the defaults are this way to say the least. > > > > I did email the author about the precision here is what he has to say: > > > > For ieee-add, it all depends on what kind of error bound you need. > > If enabled, the error satisfies > > > > |e| <= |a+b| * epsilon > > > > It not enabled, the error satisfies > > > > |e| <= epsilon * max (|a|, |b|) > > > > For most uses the second one is just fine, but some times one needs > > the > > first one. > > > > Sloppy-mul and sloppy div usually degrades by few bits, so maybe you > > lose a digit of accuracy. For double-double, the degredation is > > smaller. > > Ok. Thanks for finding out. > > > > ================ > > The answer is not qualified by processors. He didn't say anything > > about performance (I asked). > > Ok. Is there anybody out there who can run some quick test with a > decent runtime using quaddouble only in a tight loop, preferably in > pure C? We can pay in credit ;) >
By the way, my understanding is that by far the main advantage of quaddouble over mpfr is that it uses a very simple data structure, which makes quaddouble more suitable for numerical linear algebra and applications that involve supercomputing. -- William --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-devel@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
